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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 20: Complex Fluids and Soft Matter 2 (joint session DY/CPP)
CPP 20.5: Talk
Wednesday, March 24, 2021, 12:20–12:40, DYa
Particle-resolved topological defects of smectic colloidal liquid crystals in extreme confinement — •René Wittmann1, Louis Cortes2, Hartmut Löwen1, and Dirk Aarts2 — 1Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Germany — 2Department of Chemistry, University of Oxford, UK
Hard particles are a standard model for colloidal systems and can be effectively studied within classical density functional theory (DFT). Fundamental mixed measure theory (FMMT) allows to predict the phase behavior of a hard-body fluid solely from the shape of individual particles. Recent experimental advances allow for the synthesis of colloids with a nearly hard interaction that can be analyzed on the single-particle level. Slices of such silica rods confined in a three-dimensional chamber under gravity can be considered a quasi-two-dimensional fluid that exhibits typical liquid-crystal behavior in confinement.
Applying FMMT to hard discorectangles in two dimensions, we study a smectic fluid in extreme complex confinement, where the optimal bulk layer spacing competes with the extrinsic geometric and topological constraints. As a result, we characterize a variety of topologically different states in an annular geometry, also observed in particle-resolved experiments with silica rods. By further comparing the free energy of the different states, naturally provided by our DFT, we map out a topological phase diagram, indicating the stable topology depending on the details of the annular geometry.
Publication: R. Wittmann et al., Nat Commun 12, 623 (2021).